What a Power Rating Tells Us

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All day long, and throughout the night we have electricity working for us in so many different ways. We can purchase it from the power company that delivers it to our meter. Alternatively, we can buy ‘canned electricity’ in batteries. The rate with which we consume energy determines our electrical energy cost. An appliance power rating tell us how much electricity it uses.

How Appliance Power Ratings Work

power rating
Vacuum Cleaner: Jessica Spengler: CC 2.0

Power equals the rate at which the appliance does its work. Thus we can expect a higher-rated vacuum cleaner to soak up the dust faster.

However, this benefit does come at a disadvantage, because we are using more electricity that we pay for. Thus, we need to set off the extra benefits against the added cost.

Take a corded electric drill for example, as opposed to a cordless rechargeable one. If we just plan to do a few light jobs around the house, then one with a 500-watt power rating should do the job. However, we will need a more powerful one if we want an effective hammer action to drill through concrete.

Using a Power Rating to Calculate Consumption

power rating
Desktop Computer: Kevin Jarrett: CC 2.0

Let’s say, for example we want to find out the annual operating cost of a desktop computer with flat screen. The one we are considering purchasing has a power rating of 80 watts.

We plan to use it at night to surf the internet for three hours, and we will do this every day except Sundays because we keep the time for our family.

The formula we use is [hours of daily use]times [number of days a year]times [power rating]. Our answer is [3 x 312 x 80] / 100] = 74.8 kilowatt-hours a year. We can convert this to dollars according to the actual kilowatt-hour rate we pay.

We could lower this cost significantly by allowing the computer to go to sleep while we are helping the kids with their homework. The lower power rating could reduce the electricity cost by up 95%, depending on the system design and settings of the device.

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About Author

I tripped over a shrinking bank balance and fell into the writing gig unintentionally. This was after I escaped the corporate world and searched in vain for ways to become rich on the internet by doing nothing. Despite the fact that writing is no recipe for wealth, I rather enjoy it. I will not deny I am obsessed with it when I have the time. I live in Margate on the Kwazulu-Natal south coast of South Africa. I work from home where I ponder on the future of the planet, and what lies beyond in the great hereafter. Sometimes I step out of my computer into the silent riverine forests, and empty golden beaches for which the area is renowned. Richard

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